This invention relates to a cellular-structure glass or foamed glass in which at least one metallic or nonmetallic reinforcing material in the form of relatively small pieces or particles is dispersed for enhancement of heat resistance as well as mechanical strength. The heat resistant foamed glass is chiefly for use as a building material.
Recently foamed glass has been attracting much interest as a lightweight and heat insulating material that may be used in buildings and other constructions Thus far, however, applications of foamed glass are limited by reason of weakness against external mechanical force and against heating. Foamed glass of relatively high porosity is easily broken by a mechanical shock and collapses by rapid heating to 300-400.degree. C.
Low resistance of foamed glass to rapid heating with flames is attributed to the principal features of foamed glass. When a foamed glass plate or block is rapidly heated on one side thereof a steep temperature gradient is created in the foamed glass body due to lowness of heat conductivity, and the temperature gradient causes cracking of the foamed glass. Besides, rapid expansion of gases confined in the foamed glass and also gasification of a residue of the foaming agent accelerate collapsing of the heated foamed glass body.
It is known to reinforce foamed glass or ceramics by embedding or dispersing therein metal fibers as shown, for instance, in JP-A No. 60-36384. However, improvements in heat resistance including resistance to thermal shocks are deemed still insufficient.
Also it has been proposed to reinforce foamed glass or ceramics with nonmetallic mineral materials. JP-A No. 52-15603 shows a foamed glass containing a large amount of inorganic refractory material such as quartz, alumina and/or zircon together with talc and/or clay. JP-A No. 58-135153 shows a foamed glass containing a laminar mineral such as mica or vermiculite, and Journal of Materials Science, 16 (1981), 800-808 also shows a foamed glass containing mica powder. However, foamed glass containing a large amount of refractory material is rather low in mechanical strength and high in water absorption and, hence, is unsuitable as a building material. The proposed addition of a laminar mineral does not result in sufficient enhancement of resistance of foamed glass to thermal shocks.